/Engine/Plugins/Runtime/MeshModelingToolset/Source/ModelingComponents/Public/Transforms/TransformGizmoDataBinder.h
In local coordinate destination mode, when a DisplaySpaceTransform is not available on the gizmo, this default transform can be used instead. Currently, this is used to allow destination mode for the 2D gizmos in UV editor, but that's a fairly specific use case.
void SetDefaultLocalReferenceTransform ( [TOptional](API\Runtime\Core\IO\TOptional)< FTransform > DefaultTransform )